Gene therapy and genome editing in the retina

Inherited retinal diseases (IRD) are a major cause of blindness worldwide mostly due to mutations in genes expressed in retinal photoreceptor cells (PR). Recently, our lab has contributed the development of safe and effective gene therapy using adeno-associated viral vectors (AAV). This has led to the approval of the first gene therapy product for an ocular disease (Luxturna) which treats patients with a rare form of inherited childhood blindness. However, several genes expressed in PR and involved in IRD are larger in size than the carrying capacities of AAV vectors. Our goal is to overcome the challenge of transferring large genes to PR in order to develop therapies for common IRDs. Retinal gene therapy has limited applicability in the treatment of dominant IRDs. This is because these diseases are due to gain-of-function mutations for which traditional gene replacement is ineffective. We are evaluating several AAV- and CRISPR-Cas9- based approaches that allow simultaneous blocking of the mutant allele and replacement with a wild type copy. The results from these projects may provide novel treatment options for common severe blinding conditions.

Liver gene therapy and genome editing for mucopolysaccharidosis VI

Mucopolysaccharidosis VI (MPS VI) is caused by deficient arylsulfatase B (ARSB) activity, resulting in lysosomal storage of glycosaminoglycans (GAGs). MPS VI is characterized by dysostosis multiplex, organomegaly, corneal clouding, and heart valve thickening without central nervous system involvement. Enzyme replacement therapy for MPS VI has limited efficacy and requires multiple administrations of costly enzymes. Gene transfer to a factory organ like the liver may provide a life-time source of secreted ARSB. We have shown that single intravascular administration of adeno-associated viral vectors (AAV) 2/8-TBG-ARSB in MPS VI is both safe and effective in animal models and, more recently in humans, with therapeutic levels of ARSB produced by liver that are stable for several years. The long-term outcomes of gene therapy in patients as well as AAV vector dose-refining are in progress. Patients under 4 years of age are currently excluded from trials because potential hepatocyte proliferation may result in AAV episomal DNA dilution and loss of transgene expression. We are evaluating an AAV- and CRISPR Cas9-based approach that integrates the ARSB coding sequence at the highly transcribed albumin locus to obtain stable therapeutic levels of ARSB following newborn administration in animal models. This could be applied to other models of lysosomal storage diseases targetable by liver gene therapy.

Lab Manager:Mariangela Lupo
PostDoc: Fabio Dell'Aquila, Rita Ferla, Emanuela Pone
Ph.D. Student:   Federica Esposito, Arjun Padmanabhan
Fellow: Paula Sureda Horrach, Simone Notaro
Technicians:  Stefano Auricchio, Antonella Ferrara
Students: Roberto di Cunto

1. Therapeutic homology-independent targeted integration in retina and liver. Nature Communications, 2022
2. Allele-specific editing ameliorates dominant retinitis pigmentosa in a transgenic mouse model. American Journal of Human Genetetics, 2021
3. Intein-mediated protein trans-splicing expands adeno-associated virus transfer capacity in the retina. Science Translational Medicine, 2019
4. Triple Vectors Expand AAV Transfer Capacity in the Retina. Molecular Therapy, 2017 
5. Non clinical safety and efficacy of a recombinant AAV2/8 vector administered intravenously for treatment of mucopolysaccharidosis type VI. Molecular Therapy - Methods & Clinical Development, 2017
   

Complete List of Published Work in MyBibliography.